Cleaning apparatus for fibrous material



March 9, 1965 5.1.1151. 3,172,165

CLEANING APPARATUS FOR FIBROUS MATERIAL Filed Oct. 23. 1961 2 Sheets-Sheet l 8088) J. HELM //v VENTOR HUEBNER 8 WORREL A TTORNEKS March 9, 1965 B. J- HELM CLEANING APPARATUS FOR FIBROUS MATERIAL 2 Sheets-Sheet 2 Filed Oct. 23, 1961 8088) J. HELM INVENmR HUEBNER 8 WORREL A HORNEKS United States Patent 3,172,165 CLEANTNG APPARATUS FOR FIBROUS MATERIAL Bobby JrHelm, Fresno, Calif. (R0. Box 128, Laton, Calif.) Filed 0st. 23, 1961, Ser. No. 146,873 5 Claims. (Cl. 19203) The present invention relates to a cleaning apparatus for fibrous particles of materials such as wool, kapoiz, cot-ton and the like. The invention relates particularly to such a cleaning apparatus utilizing air as a conveying vehicle and having specific utility for cotton picking, stripping and gleaming machines.

The mechanism provides two potential cleaning cycles having first and second cleaning stations whereby the second station processes only that cotton rejected from the first cleaning station and returns the same back into the conveying air stream at a point upstream of the first cleaning station.

During the harvesting of cotton and other fibrous crops, the machines conventionally employed for the purpose usually pick up a substantial amount of foreign material such as dirt, trash, cotton bolls and bits of stalk from the plants along with cotton being picked. Due to the fibrous low-density composition of cotton, it is easily penetrated by and intertwined with such foreign material. Therefore, subsequent separation is extremely d-ifiicult.

The conventional machines further utilize ducted highvelocity low-pressure air for conveying the cotton from a picking zone adjacent the ground to a collecting container on the machine. During such transport, the cotton and trash are tumbled and further agitated which augments the tendency for intermixing of the materials. The prior art has attempted to solve this problem by providing various mechanisms interposed the picking zone and the collecting container. Such attempts have not heretofore been commercially feasible since they either do not remove all of the trash from the cotton or reject a substantial amount of usable cotton along with the trash :being separated therefrom. Furthermore, in order eiiectively to overcome both of these disadvantagesthe prior art mechanisms provide structures which are unduly complicated and frequently are of a cumbersome size not readily adapted to existing harvesters.

Specifically, the prior art has resorted to dual-cycle cleaning mechanisms. Such mechanisms usually employ large, rotatable, cylindrical saw drums having teeth on which the cotton and intertwined trash are impaled. A plurality of toothed rollers or brushes are operationally associated therewith to remove the trash from the cotton which operation must be accomplished without removing the cotton from the drum. Additional dofiing brushes are also necessary subsequently to remove the cotton from the saw drum into a second cleaning station identical to the first. The multiplicity of rollers, brushes and saw drums in such mechanisms are objectionable in that such structures are space consuming, require complicated controls, and are difficult to service. Another objection with these systems is that all of the cotton exhausted from the first cleaning station is directed to the second cleaning station, without regard to its trash content, thereby increasing the chance of exhausting a portion of the usable cotton along with the trash.

Therefore it is an object of the present invention to provide a cleaning mechanism for fibrous material such as cotton and the like which efiectively separates sub stantially all of the foreign material therefrom with a minimum of loss of usable material.

Another object is to provide a cleaning mechanism having two potential cleaning cycles.

Another object is to provide a cotton cleaning mechanism having first and second cleaning stations wherein only cotton with entrained trash rejected by the first cleaning station is permitted to enter the second cleaning station.

Another object of the present invention is to provide such a cleaning mechanism having dual cleaning stations wherein the second cleaning station exhausts clean cotton into the conveying air stream ahead of the first cleaning station selectively tor reclaiming or being exhausted with incoming clean cotton.

Another object is to provide a cotton cleaning mechanism providing individually adjustable trash cut-ofl? plates adjacent to each of the first and second cleaning stations to control and minimize the dropping of usable cotton with exhausted trash.

Another object is to provide such a cleaning mecha nism which is simply and economically constructed, is easily controlled and is readily adapted to existing harvesters.

Other objects and advantages of the present invention will become more .fully apparent in the subsequent description in the specification.

In the drawings:

FIG. 1 is .a vertical section taken on a plane centrally through the mechanism of the present invention with portions of the internal structure shown in side elevation.

FIG. 2 is a fragmentary top plan view of the mechanism of FIG. 1 with portions broken away for illustrative convenience.

PEG. 3 is a side elevation of the mechanism of FIGS. 1 and 2 showing the trash control members and the cleaning station drive mechanism.

Referring more particularly to the drawings, the cleaning mechanism embodying the principles of the present invention is indicated generally at 10. The mechanism is supported in a generally rectangular housing 11 constructed of opposite side plates 14 interconnected by opposed front and rear plates 15 and 16, respectively, all of lightweight sheet metal material. The housing is divided into a lower section 17 and an upper section 18 which are joined by suit-able cooperating flanges along their adjacent edges by a plurality of bolted connections, one of which is indicated at 19. An elongated intermediate panel 20 is extended between and is rigidly secured to the opposite side plates 14 of the housing in spaced substantially parallel relation to the rear panel 16 thereof. An inlet passage 21 is thereby defined between the intermediate panel 20 and the rear panel 16. Opposite flange members 24 and 25, respectively, are provided adjacent to the lower edge of the housing. The flanges are adapted to be releasably secured, as by bolted connections, to corresponding flanges on a low-pressure high-velocity air conduit 26 provided on a cotton picking or gleaning machine, not shown, for conveying cotton therefrom to a suitable collecting container, also not shown. An air stream is propelled through the conduit 26 by means of any suitable blower schematically illustrated in FIG. 1 and connected to conduit 26. As shown viously described flanges and bolted connections.

in FIG. 3, a dirty cotton supply conduit 27 is connected to the air conduit between the blower and the inlet passages.

A pair of elongated arcuate shaped panels 30 and 31 are extended between and are rigidly secured to the side panels 14 of the housing in spaced relation to each other. Defined thercbetween is a substantially cylindrical chamber having oppositely opening upper and lower ends 32 and 33, respectively. The panels 30 and 31 are also provided with flanged brackets 34 and 35 adjacent the lower edge of the housing for connection to an exhaust conduit 38 for collecting debris exhausted by the cleaning mechanism 1.0.

The upper section 18 of the housing provides an obconnected to the lower section of the housing by the pre- The panel 40 also provides a downwardly extended flange 4 1. A top cover member 43 is pivotally secured to the upper section 18 of the housing by a hinge 44 secured to the forward panel 15 of the housing. The top includes a front panel 45, a top panel 45 and an angular rear panel 47.

The rear panel 47 includes a flange member 48 which is v aligned in coplanar relation with the flange 41 of the v lower angular panel 40. With the cover 43 disposed in the closed position of FIG. 1, an exhaust passage 50 is thereby provided to interconnect with and to be disposed Y in a plane normal to the vertically extended inlet passage side walls 14 of the housing and is supported for rotation by a shaft 58 journaled therein. The shaft is disposed in a plane vertically aligned with the intermediate panel 20 of the housing to position the drum within the inlet passage 21 but spaced from the lower panel 4d of the housing to permit interconnection between the inlet and exhaust passages. From the description thus far, it Will be readily apparent that any cotton being conveyed by the air stream within the inlet passage 21 will travel in a straight path and, unless diverted from that path, will impinge against the teeth 57 of the drum.

An elongated bracket 69 rigidly secured between the side plates of the housing rigidly mounts a brush 61 having a multiplicity of bristles 62 upwardly extended there- 4 from in sweeping engagement against the toothed periphery of the drum 56. The brush is mounted in coplanar relation with the drum shaft 58 and the intermediate panel 20. It is readily apparent that any cotton impinging tended outwardly of the side panel 14 to mount an adjustment lever 66. The lever is pivotally mounted to a substantially horizontally disposed control handle 67, having notches 68 therein engageable with a locking pawl 69. With such arrangement, it is apparent that horizontal reciprocation of the handle 67 will be effective to rock the cut-off plate 65. Such rocking causes the tip of the plate to be moved toward or away from the toothed periphery of the drum for reasons soon to be discussed in greater detail.

A rigid, non-adjustable cut-off plate 70 is disposed closely adjacent tothe toothed periphery of the drum at a position between the side plates of the housing within the exhaust passage 59. A substantially cylindrical dotting V the side plate 14 of the housing.

brush 72 is rotatably mounted in the top cover of the housing by means of a shaft 73. The brush is provided with a plurality of radially extended bristle members 74 adapted for sweeping engagement with the toothed periphery of the drum during rotation of the brush. The dotfing brush 72 is partially enclosed within the cover by a lower bafile member 75 and an upper bafile member 76 both rigidly secured to the top cover 43.

The lower section 17 of the housing encloses a second cleaning or reclaiming station generally indicated at 80. The reclaiming station includes an elongated cylindrical snagging member or drum member 82 of substantially half the diameter of the drum 56 in the first cleaning station. The drum 82 provides a plurality of spaced saw teeth 83 about its outer periphery. The drum is rotatably mounted by means of a shaft 85 journaled between the side plates of the housing. The drum is disposed in such a manner that a portion of the outer periphery of the drum is extended into the inlet passage 21 of the housing thereby defining an exhaust section of the drum. The drum is also closely adjacent to the lower curved surface of the bracket 69 and the upper edge of the intermediate panel 20. 1

An elongated scroll sheet 37 is arcuately inwardly extended from the intermediate panel 26 beneath the drum 82 to terminate at a position substantially aligned with the arcuate trash exhaust panel 30. An adjustable cut-ofi plate having upper and lower legs 91 and 92 is slidably received upon the scroll plate 87. The legs are connected by a bight portion 93 which is rigidly adapted to receive a rod 94 extended through an elongated arcuate slot 95 in A linkage similar to that provided for the adjustable cut-off plate 65 is also provided in the second cleaning station wherein a link 97 is rotatably secured to the rod 94 on the cut-off plate. The link 97 is rotatably mounted at its other end on a lever 98 which is pivotally mounted at its opposite end on a stationary rod 99 secured to the housing. A control handle 10!) having a plurality of notches 101 therein is pivotally connected to the rod 94 for manually positioning the cutoff plate 90. The link 97 and the lever 93 insure that any push-pull force on the handle is transmitted substantially tangentially of the arcuate scroll sheet 87 for free ment permits discharge of trash from the upper opening 32 through the lower opening 33 thereof without an appreciable loss of conveying air from the housing.

In order to increase the velocity of the air flowing from the inlet passage 21 to the outlet passage 50, an adjustable nozzle plate 108 is pivotally connected at 109 to the rearward wall 16 of the housing, the pivotal connection being parallel with the axis of rotation of the drum S2 of the second cleaning station. The plate108 is selectively positioned about the hinge connection 109 to control the reduction of the area of the opening provided between the plate 108 and the extended portion of the outer periphery of the drum 82. This reduction in area in relation to inlet 21 provides a venturi effective to decrease the pressure of the air passing therethrough with a corresponding and desired increase in velocity of the air stream.

With particular reference to FIGS. 2 and 3, the drive mechanism for the rotatable elements within the cleaner will now be described. As best shown in FIG. 2, each of the mounting shafts for such elements extend outwardly of the side plate 14 to be supported in suitable bearing blocks sccrde by cap-screws to the side plate.

Such drive mechanism includes a drive sprocket 110'nonrotatably secured to the drive shaft 58 supporting the drum 56 of the first cleaning station 55. As also shown in FIG. 2, the shaft 58 extends outwardly beyond the sprocket for connection to any suitable power takeoff mechanism to transmit power from the prime mover, not shown. An idler sprocket 111 is similarly mounted for rotation on a shaft 112 rigidly secured to theside plate 14 of thehousing in upwardly spaced substantially ver tically aligned relation with the drive shaft 58. The mounting shaft '73 of the doffing brush 72 associated with the first cleaning station non-rotatably mounts a sprocket 114 in coplanar relation with the sprockets 110 and 111. A sprocket 116 is non-rotatably secured to the shaft 85 of the drum 82 of the second cleaning station 80. The sprocket 116 is also in coplanar relation with the sprockets 110, 111, and 114. An endless chain 126 is trained over the side of the drive sprocket 110 nearest the doffing brush 72, around the sprocket 116, around the sprocket 114 and around the idler sprocket 111. With such arrangement, the drive sprocket for the drum 56 is rotated in a clockwise direction as viewed in FIG. 3 which through the endless chain 120 drives the sprocket 116, the sprocket 114 and the idler 111 in counterclockwise directions. With the input speed of the drive sprocket 1111 being preferably approximately 400 r.p.m., the relative diameters of the other sprockets within the drive train are such to rotate the doifing brush 72 at approximately 900 while the drum 82 of the second dofiing station is driven at approximately 200 r.p.m. A speed-reducing drive sprocket 122 is secured to the drive shaft 85 in outwardly spaced relation from the sprocket 116.

A sprocket 125 is non-rotatably mounted on the shaft 106 of the seal wheel 105 in coplanar relation with the sprocket 122. An endless chain 126 is trained about the sprockets 122 and 125 for circuitous movement therearound. The sprockets 122'and 125, of the power train completed by the chain 12am proportioned to effect rotation of the seal member 165 at approximately 60 r.p.m.

Operation The operation of the described embodiment of the present invention is believed to be clearly apparent and is briefly summarizedat this point. The blower is rotated at a speed suflicient to provide the air stream flowing through the conduit 26 with a conveying velocity of approximately two thousand feet per minute. 'Such a velocity is a normally accepted velocity in cotton transporting ducts employing an air stream as the conveying vehicle. The inlet passage 21 constrains the air stream, including the cotton and trash entrained therein, to a substantially straight vertical path of travel prior to 'reach ing the separating portion of the apparatus. To further accelerate the air stream, as well as the particles of cotton and trash, the plate 103 is adjustably positioned about the pivotal connection 109 to reduce the area of the venturi throat defined by the plate 108 and drum 82. The area is reduced a sufiicient amount to cause the desired increase in air velocity. One of the purposes of increasing the velocity at this point is to provide a highvelocity air stream flowing over the periphery 'of the second cleaning drum thereby to serve as a means to doff the cotton from the peripheral teeth of that drum.

The air stream flowing through the conduit 26 carries the intermixed cotton and trash substantially vertically upwardly against the periphery of the drum 56.

During rotation of the drum 56, the contaminated cotton particles engaging the teeth 57 will be carried to 'the right as viewed in FIGURE 1, and passbetween the each cotton particle is carried further to the right, any

projecting particles of trash contact the cut-off plate 65,

which is adjusted to an optimum cleaning position. The

cut-oil plate thereby restricts the movement between the 'drum and the plate of any cotton having trash entrained therein and deflects particles of trash, as well as heavily contaminated cotton particles, downwardly toward the second cleaning station. It is noted that a substantial amount of the heavier contaminated cotton is thrown downwardly by centrifugal force prior to cont-act with the cut-off plate. The relatively cleaner cotton remains on the drum and is then successively engaged by the plurality of grid bars which further agitate and knead the cotton effectively to disengage any remaining trash which might have remained therein. Such'trash also is gravitationally directed into the second cleaning station to be exhausted as explained below. The clean cotton continues to rotate with the drum until reaching the dofilng brush 72. The'bristles 74 having a greater peripheral speed than the teeth 57 sweep the cotton from the teeth of the drum and into the air stream of the exhaust passage 51). The stationary plate is effective to block the air stream from the dofiing brush and thereby avoid undesirable eddy currents while directing the air stream in its desired curvilinear path.

The contaminated cotton rejected from the first cleaning station 55 gravitationally falls upon the angularly declining brush 1193 where it is engaged by and impaled upon the teeth of the drum 82. If the adjustable cutoff plate MP is positioned at its fully closed position adja'c-ent the brush 103, the plate prevents any cotton from falling into the trash exhaust 38. However, when the cut-off plate is adjusted to a position spaced from the brush an opening is thereby provided to permit trash disengaged by the cut-cit plate to gravitate into the rotating member 105. The cotton impaled upon the teeth 83 is thereby rotated with the drum back into the inlet chamber 21 of the housing where it is dotted therefrom by the incoming air stream which has been accelerated upon passing through the venturi throat. The cotton dotted from the drum 82 is again directed against the drum 56 and into the first cleaning station. This process is repeated until the trash is removed from the cotton so as to permit the force of the air stream to accelerate the cotton to the curvilinear path past the first cleaning station or to direct it through the first cleaning station for subsequent dofling by the brush 72.

The adjustment of the cut-off plates 65 and is correlated so as virtually to eliminate the exhausting of usable cot-ton through the trash exhaust 32, 33 and 38. Such correlation is accomplished by first moving the control handle 10 0 to the left, as viewed in FIG. 3, of the second station cut-off plate 90 to determine if the first station cutotf p'late65 is permitting an unusually large amount of cotton to drop into the second station. If such is the case, the first station cut-off plate 65 is opened by movement of the control handle 67 to the left, also as viewed in FIG. 3, an amount sufiicient to permit substantially all of the cotton to pass between the cut-off plate and the periphery of the drum. The lower cut-off plate 90 is then adjusted to provide the largest opening between the plate and the brush to permit the maximum discharge of trash without dropping cotton. The cut-off plate 65 is then re-adjusted, if required, by movement of the control handle 67 to the right. The need for such adjustment is easily determined by observing the cotton exhausted through the outlet passages 38 and 50.

From the foregoing, it is readily apparent that the mechanism of the present invention is effective to clean and retain substantially all of the cotton passing therethrough with a minimum of usable clean cotton being lost number of rotary elements as compared to that required by conventional machines which do not provide the effective cleaning performance of the instant structure. Also,

the present structure automatically selectively eliminates incoming clean cotton from the cleaning operation so that the mechanism is not overloaded as in conventional machines wherein the total quantity of cotton introduced into the cleaning apparatus must be processed, the clean, as well as the contaminated, cotton. Although the present structure provides a second cleaning station, cotton cleaned sufficiently by the first station is ejected from the mechanism without entering the second station. Of further importance is that the inlet air stream is utilized for dofiing cotton impaled on the saw drum 82 of the second cleaning station which eliminates the additional dofiing brushes required by conventional machines.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention,

- which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A cotton cleaner comprising a housing having interconnected inlet and outlet passages; a blower connected to said inlet passage to supply a predetermined quantity of air as a conveying stream; means to introduce into the stream a quantity of cotton particles, including clean particles intermingled with particles contaminated by and intertwined with foreign material; means to direct the conveying air stream and particles entrained therein in a predetermined path of travel; first rotary means mounted in the housing in aligned relation with "said path to receive said cotton particles and to remove them from the air stream; adjustable means mounted in the housing to remove the foreign material from said cotton particles; and second rotary means to strip the cotton particles from the first rotary means and to reintroduce them into the conveying air stream, said first rotary means being rotatable at a rate sufiicient to eject centrifugally the heavier portions of contaminated cotton; and third rotary means in the housing below said first rotary means to receive said ejected particles and to remove the foreign material therefrom, the third rotary means having a portion of its periphery exposed to the air stream in said inlet passage.

2. A cotton cleaner comprising a housing having interconnected inlet and outlet passages; a blower connected to said inlet passage to supply a predetermined quantity of air as a conveying stream; means to introduce into the stream a quantity of cotton particles, including clean particles intermingled with particles contaminated by and intertwined with foreign material; means to direct the conveying air stream, said inlet passage including means I to provide an adjustable venturi throat adjacent to said third rotary means whereby the conveying air stream is accelerated past the third rotary means to serve as a dofiing medium to remove cotton particles carried by said third rotary means.

3. Apparatus for cleaning particles of low density fibrous material, some of the particles having intertwined therewith and contaminated by particles of foreign material, comprising a sealed housing; inlet and outlet passages connected therewith; a blower connected to said inlet passage to introduce an air stream at a predetermined velocity having entrained therein said fibrous particles, including both clean and contaminated particles;

enclosure means interconnecting said inlet and outlet passages to provide a predetermined path of travel for said air stream; a first cylindrical member mounted for rotation in the housing and having a toothed periphery providing a portion disposed within said path of the air stream, said first cylindrical member being rotated in a direction so that the peripheral portion Within Said air stream path moves in a direction substantially normal thereto; means mounted in the housing downstream from said path and adjacent to the first cylindrical member to sweep fibrous particles from the toothed periphery; a second cylindrical member powered for rotation in the housing and having a toothed periphery to engage the fibrous particles, the second member being disposed in the housing beneath said first cylindrical member gravitationally to receive fibrous particles detached from the first member by centrifugal force; an adjustable plate mounted in the housing adjacent tosaid second cylindrical member to extract foreign material from fibrous particles engaged by and carried on the toothed periphery on the second cylindrical member, the second member being disposed with a portion of its periphery exposed to the air stream in the inlet passage; and means in the inlet passage adjacent to said exposed periphery to constrict said air 'stream flowing over said periphery thereby to increase the air stream velocity to a value sufiicient to sweep from said exposed periphery any fibrous materials clinging thereto.

4. A cotton cleaning apparatus, providing an air stream in a predetermined path for conveying cotton having foreign material mixed therewith, comprising a first rotary snagging member disposed within the path of said air stream to snag such cotton from the air stream and centrifugally to separate such foreign material therefrom and to eject the same in a predetermined discharge path with Whatever cotton inadvertently remains intermixed therewith, and a second rotary snagging member positioned in said discharge path to receive foreign material and cotton ejected by said first snagging member for 7 further centrifugal separation of the foreign material from the cotton and having an exhaust section disposed in said air stream in advance of the first rotary snagging member whereby cotton on the second rotary snagging member is dotted by the air stream bearing the cotton and foreign material.

5. Apparatus for cleaning particles of low density fibrous material, some of the particles having intertwined therewith and contaminated by particles of foreign material, comprising a sealed housing having inlet and outlet passages; a blower connected to said inlet passage to introduce an air stream at a predetermined velocity having entrained therein said fibrous particles, including both clean and contaminated particles; a plurality of spaced panels defining an intermediate passage interconnecting said inlet and outlet passages and having a substantially straight portion and an open arcuate portion to provide a predetermined path of travel for said air stream; a first cylindrical drum mounted for rotation in the housing and having a toothed periphery disposed within said intermediate passage to define a wall for said open arcuate portion and being in substantial alignment with said straight portion of the intermediate passage in partial interfering relation to said air stream, said first cylindrical drum being rotated in a direction so that the periphery interfering with said air stream path moves in a direction substantially normal thereto; a plurality of grid bars mounted in the housing adjacent to the periphery of the cylindrical member to engage particles of fiber enmeshed with the toothed periphery; a rotary brush mounted in the housing downstream from said path and adjacent to the first cylindrical drum to sweep fibrous particles from the toothed periphery; a second cylindrical drum powered for rotation inthe housing and'having a toothed periphery to engage the fibrous particles, the second drum being disposed in the housing beneath said first cylindrical member gravitationally to receive fibrous particles detached from the first drum by centrifugal force and by said grid bars; an adjustable plate mounted in the housing adjacent to said second cylindrical member to extract foreign material from fibrous particles engaged by and carried on the toothed periphery on the second cylindrical drum, the second drum being disposed with a portion of its periphery exposed to the air stream in the inlet passage; and means in the inlet passage adjacent to said exposed periphery to constrict said air stream flowing over said periphery thereby to increase the air stream velocity to a value sufficient to sweep from said exposed periphery fibrous materials clinging thereto.

References Cited by the Examiner UNITED STATES PATENTS 661,166 11/00 Boyd 19205 X 3/04 Rollins 19-205 X 8/11 Broome 209-135 2/54 Gieszl 209138 5/56 Wallace 19203 4/58 Day 19--203 11/59 Hunter 19--203 3/ 60 Massey et a1 19--205 12/62 Vandergriff 19203 10/63 Moss et a1. 19202 FOREIGN PATENTS 1/ 24 France.

3/22 Great Britain.

8/ 31 Great Britain.

8/ 33 Great Britain.

DONALD W. PARKER, Primary Examiner. 

4. A COTTON CLEANING APPARATUS, PROVIDING AN AIR STREAM IN A PREDETERMINED PATH FOR CONVEYING COTTON HAVING FOREIGN MATERIAL MIXED THEREWITH, COMPRISING A FIRST ROTATY SNAGGING MEMBER DISPOSED WITHIN THE PATH OF SAID AIR STREAM TO SNAG SUCH COTTON FROM THE AIR STREAM AND CENTRIFUGALLY TO SEPARATE SUCH FOREIGN MATERIAL THEREFROM AND TO EJECT THE SAME IN A PREDETERMINED DISCHARGE PATH WITH WHATEVER COTTON INADVERTENTLY REMAINS INTERMIXED THEREWITH, AND A SECOND ROTARY SNAGGING MEMBER POSITIONED IN SAID DISCHARGE PATH TO RECEIVE FOREIGN MATERIAL AND COTTON EJECTED BY SAID FIRST SNAGGING MEMBER FOR FURTHER CENTRIFUGAL SEPARATION OF THE FOREIGN MATERIAL FROM THE COTTON AND HAVING AN EXHAUST SECTION DISPOSED IN SAID AIR STREAM IN ADVANCE OF THE FIRST ROTARY SNAGGING MEMBER WHEREBY COTTON ON THE SECOND ROTARY SNAGGING MEMBER IS DOFFED BY THE AIR STREAM BEARING THE COTTON AND FOREIGN MATERIAL. 